Considering the game got bogged down with enough legal nonsense as it was, probably got to the point where it simply was already too expensive to allow for paying for new voice work with the expected sales.It's certainly the exception rather than the rule.

<SaturnineTenshi> and we can play with solice because he likes it<Solice> i hear it's better than playing with myself

<Solice> celtic had a hard time getting his ball out?<Kana> oh man, you have no idea

I think another issue was it being digital download only and being on PSP which only survives outside of Japan by the very few games that get localized for it anymore and people who own a PS Vita. All of NISA's digital download only games have no English dub even on PS3.

Atelier Annie also didn't have an English dub but that was because of DS games size limit and not trying to make it English dub voices only.